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Seeing Through History

The ruins of the ancient city of Tikal in Guatemala.
In 1925, British explorer Percy Fawcett set off into the jungles of Brazil looking for the fabled Lost City of Z. Fawcett and his three companions knew the trip would be dangerous. They would likely face ferocious animals, poisonous plants, and deadly diseases. But in Fawcett's mind, the potential discovery was worth the risk. He believed that the City of Z contained the secrets of a significant ancient culture. After several weeks of exploration, however, Fawcett and his team disappeared without a trace.
Today, thanks to advancements in transportation, exploring the world isn't nearly as risky as it was in 1925. Planes and helicopters enable scientists, archaeologists, and adventurers to reach many remote areas with ease. And perhaps even more vital than the vehicles themselves is a piece of technology they often carry, known as lidar. Created in the 1960s, lidar has become an indispensable tool that allows researchers to locate land formations and man- made sites they might otherwise miss, including those that have been buried under trees, plants, or water over thousands of years.
Lidar stands for Light Detection and Ranging. It is similar to radar, but it uses light instead of radio waves to map objects and landforms. This allows lidar to produce exceptionally detailed images, offering scientists what amounts to archaeological X- ray vision. In its most basic form, lidar involves a plane or drone using a laser to aim pulses of light at the surface of the earth. When these pulses reach land, they "bounce" back to the vehicle, where sensors measure and record the distance traveled by the laser beam. Most hit trees and leaves, but a small percentage of the hundreds of thousands of pulses reach solid objects— such as hidden ruins. And by selecting only these pulses, scientists can get a much clearer picture of the "naked" landscape beneath the jungle canopy, allowing them to create a three- dimensional map of the area.
These new lidar maps are motivating researchers to reconsider what they thought they knew about ancient peoples. One famous lidar study was done in Guatemala in the area surrounding the ancient Mayan city of Tikal. Archaeologists were fairly confident that they had an accurate picture of this area. But in just one summer of lidar mapping, scientists realized that Tikal was five times larger than they'd previously thought.
In fact, one scan of the region showed that an area previously believed to have been swampland during the Mayan empire was actually farmland crisscrossed by a vast series of man- made canals and reservoirs. Why would a community living in a lush rainforest need to store water? Based on this new information, some experts argue that this area of Guatemala, which is now covered in dense jungle, may have once been an open savannah that suffered from occasional droughts.
In addition to uncovering details about Tikal and other sites in Central and South America, lidar technology has been instrumental in detailing the Roman ruins of Italy. It has even provided vital information about World War I and World War II camps, graveyards, and battle sites across the European continent.
Before lidar, many doubted that Percy Fawcett's "lost" city ever existed. But new lidar information suggests that ancient cities once flourished in the area where the explorer went missing. Although we may never uncover all the secrets of the Lost City of Z, lidar will continue to shine new light on humanity's most captivating mysteries.
What is the text mainly about?
It is mainly about lidar technology and how it has helped scientists find answers to many archaeological mysteries.
It is mainly about how explorers like Percy Fawcett risk their lives to find evidence of hidden civilizations.
It is mainly about why scientists believe lidar can never replace planes and helicopters in archeological mapping.
It is mainly about the way lidar technology is making archaeological exploration irrelevant.
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